Novel high-temperature four-parameter steam absorption profile tester

Abstract

The invention discloses a novel high-temperature four-parameter steam suction profile tester, which relates to the technical field of heavy oil thermal recovery steam injection well shaft steam parameter and steam suction profile testing, is based on the existing high-temperature heat insulation and high-pressure sealing temperature and pressure measurement technology, and ingeniously applies a pitot tube measurement principle to measure speed and a related mass-energy relational expression. Measurement of steam flow and dryness is achieved, measurement of all parameters of shaft steam and an oil layer steam absorption profile are obtained, the problem that at present, the dryness of underground steam is obtained only through calculation is solved, and meanwhile the problem that application of testing the steam flow through a turbine flowmeter is limited is solved. According to the invention, the testing of four high-temperature parameters of underground steam and the steam absorption profile is really realized, the urgent production problem of a thickened oil steam injection well is solved, real and remarkable benefits are brought to the development and production of thickened oil, and the method has a wide application prospect.

Description

Technical Field

[0001] This invention relates to monitoring technology for steam injection wells in heavy oil thermal recovery, and is particularly suitable for the accurate measurement of steam temperature, pressure, flow rate, dryness, and steam absorption profile under high temperature and high pressure environments. Background Technology

[0002] The development of the high-temperature four-parameter steam absorption profile tester began in the 1990s. It utilizes high-temperature insulation, high-pressure sealing, and differential pressure measurement technologies to test wellbore steam temperature, pressure, flow rate, dryness, and reservoir steam absorption profile. Differential pressure technology was initially applied to flow rate and dryness measurement, but this approach was abandoned due to the immaturity of differential pressure sensor technology. Instead, a turbine flow meter was used to measure flow rate, and steam dryness was calculated theoretically, leading to the current high-temperature four-parameter steam absorption profile tester. For over 20 years, the high-temperature steam absorption profile tester has been widely used in various heavy oil development blocks in China, becoming a major thermal recovery monitoring device. The instrument's main working principle is as follows: Temperature is measured using a PT100 platinum resistance sensor; pressure is measured using a silicon sapphire sensor; steam dryness is calculated based on wellbore heat loss; inter-layer rotational speed is measured using a turbine flow meter, and decreasing analysis is applied to calculate steam stratification flow rate and steam absorption profile.

[0003] Existing high-temperature four-parameter testers rely on turbine flow meters and theoretical calculations of dryness, which have the following drawbacks: 1. Turbine flow meters exhibit significant errors during steam phase change; 2. The dryness calculation model has many parameters and large errors.

[0004] 3. It is impossible to directly obtain the steam absorption parameters of each sublayer of the oil reservoir. Current high-temperature four-parameter vapor absorption profile testing instruments can no longer meet the needs of fine reservoir monitoring in later stages of heavy oil development, and technological innovation is urgently needed. This invention improves the Pitot tube to directly measure dynamic pressure difference and combines it with the mass-energy equation to achieve simultaneous and accurate testing of four parameters. Summary of the Invention

[0005] The purpose of this invention is to develop a technology for measuring downhole steam flow rate and dryness based on the existing high-temperature four-parameter tester temperature and pressure test design, using the Pitot tube velocity measurement principle, so as to truly realize the measurement of downhole steam temperature, pressure, flow rate, dryness and oil reservoir steam absorption profile.

[0006] To achieve the above objectives, the present invention provides a novel high-temperature four-parameter steam absorption profile tester, comprising: Pitot tube design: Based on the conventional L-shaped Pitot tube design, structural improvements are made to meet the requirements of downhole space location and shape size.

[0007] The Pitot tube diameter is designed to be 6mm, the full pressure hole diameter is designed to be (0.3-0.8D), take 1.8mm, and the static pressure hole diameter is designed to be 1mm; the distance between the full pressure hole and the static pressure hole is (3-8D), take 30-40mm, and the distance between the static pressure hole and the thermos bottle's cut-off surface is 70-80mm.

[0008] Thermos bottle design: Based on the main structure of the current high-temperature four-parameter vapor absorption profile tester, the thermos bottle structure is improved and a special-shaped thermos bottle is designed with a diameter of 32mm and a length of 1200mm.

[0009] Anti-turbulence suspension design: The anti-turbulence suspension is designed to ensure the normal operation of the Pitot tube without hindering the instrument's suspension and testing within the wellbore.

[0010] Overall working principle and testing process of the instrument: The new storage-type high-temperature four-parameter tester uses a thermos bottle for insulation. The temperature and pressure measurement modules follow existing technology and basic design, placing the temperature sensor and pressure-sensing diaphragm box outside the thermos bottle, while the pressure sensor, miniaturized circuit, battery, and other components are placed inside. The differential pressure measurement module circuit is located inside the thermos bottle. It is powered by a 3.6V battery with a temperature resistance of 150℃. The instrument can operate normally for 2-3 hours in a high-temperature environment of 360℃.

[0011] Downhole data acquisition and storage are implemented using a microcontroller system. The microcontroller CPU periodically acquires signals from the temperature sensor according to pre-input parameters, converts them via an analog-to-digital converter (A / D converter), and stores the data in memory. After the test is completed, the data is retrieved via a ground-based computer.

[0012] The instrument is lowered using a test wire to test the steam injection parameters and steam intake profile of steam injection wells; multiple tests at equal intervals can be performed inside the wellbore; and multiple tests can also be performed inside the oil layer by arranging test points according to the number of sub-layers.

[0013] Technical specifications: Outer diameter: 32mm; Length: 1350mm; Temperature measurement range: -20~360℃, accuracy ±1℃; Pressure measurement range: 0~40MPa, accuracy 0.1%FS; Differential pressure measurement range: 0.1-0.2MPa, maximum static pressure ≤20MPa, accuracy 0.1%FS.

[0014] Measurement methods The dynamic pressure difference ΔP is obtained through a pitot tube. Calculate the steam density ρ using temperature T and pressure P; The improved algorithm was used to calculate the flow velocity V and dryness fraction X. Multi-point measurements generate a three-dimensional vapor absorption profile (mass, volume, heat).

[0015] Application Examples During the stable steam injection period of well K32-03, the boiler outlet parameters were: steam temperature 334℃, steam pressure 13.5MPa, steam discharge 14t / h, and steam dryness 75%. One boiler per well was used for steam injection, with a surface pipeline length of 600m. Wellhead steam parameters were: temperature 296.48℃ and pressure 8.271MPa. A total of 13 measuring points were set up for this test: 8 points inside the wellbore (1 point per 100 meters), 1 point at the bell-shaped inlet, and 3 points in each of the 3 oil-bearing sections. The measured temperature, pressure, and differential pressure data are shown in the table below.

[0016] Table 1 Test Data Table

[0017] The parameters for testing inside the wellbore (temperature, pressure, dryness, flow rate), the parameters for testing within the oil layer (temperature, pressure, dryness, flow rate), and the steam absorption of the sub-layers were determined according to the aforementioned specific implementation method. The calculation results are shown in the table below.

[0018] Table 2 Results of Wellbore Parameter Test and Analysis

[0019] Technical effect Direct measurement of four parameters breaks through the limitations of traditional indirect calculation, enabling direct measurement of downhole steam temperature, pressure, flow rate, and dryness, with significantly improved accuracy; Solve the failure problem of turbine flow meters under phase change conditions; Direct measurement of dryness reduces the error from 30% to less than 5%. Multi-dimensional steam absorption profile analysis supports oil reservoir steam absorption profile analysis in three dimensions: mass, volume, and heat. It has wide applicability, covering the testing needs of high pressure (≤40MPa), high temperature (≤360℃) and complex well conditions (multi-layer, long well section), and is adaptable to 360℃ / 20MPa environment, completing full parameter testing in one well run. Attached Figure Description

[0020] The above and other objects, features and advantages of the present invention will become more apparent from the more detailed description of exemplary embodiments of the invention in conjunction with the accompanying drawings, wherein the same reference numerals generally represent the same components in the exemplary embodiments of the invention.

[0021] Figure 1 A schematic diagram of an improved Pitot tube velocimetry principle of a novel high-temperature four-parameter steam absorption profile tester according to an embodiment of the present invention is shown.

[0022] Figure 2 The diagram shows a non-standard thermos bottle and instrument structure design of a novel high-temperature four-parameter vapor absorption profile tester according to an embodiment of the present invention.

[0023] Figure 3 A structural diagram of the instrument assembly of a novel high-temperature four-parameter steam absorption profile tester according to an embodiment of the present invention is shown.

[0024] Figure 4 The diagram shows an anti-turbulence suspension design for a novel high-temperature four-parameter steam absorption profile tester according to an embodiment of the present invention.

[0025] Explanation of icon numbers 1. Full pressure port; 2. Static pressure port; 3. Differential pressure module; 4. Thermos bottle; 5. Pressure guiding port; 6. Temperature sensor head; 7. Temperature and pressure measurement module; 8. Anti-turbulence suspension. Detailed Implementation

[0026] Preferred embodiments of the invention will now be described in more detail. While preferred embodiments of the invention are described below, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the invention will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0027] This invention provides a novel high-temperature four-parameter steam absorption profile tester, comprising: 1. Measurement Principles and Methods (1) The differential pressure at the downhole measuring point is recorded by the improved Pitot tube device, and the temperature and pressure values ​​are measured simultaneously.

[0028] A pitot tube is a commonly used flow velocity measuring instrument, based on the laws of conservation of momentum and mass in fluids. It is suitable for measuring the flow velocity of liquids and gases and is widely used in various fields.

[0029] Standard pitot tubes come in L-type and S-type. An L-type pitot tube is made of two concentrically connected stainless steel tubes of different diameters. The inner tube, connected to the straight end connector, is the full-pressure section, while the outer tube, connected to the side connector, is the static pressure section. The pointing rod aligns with the probe head, allowing for direction determination during use and ensuring the probe is aligned with the incoming flow direction. An S-type pitot tube consists of two tubes of the same diameter facing away from each other. The windward side is the full-pressure section, and the leeward side is the static pressure section.

[0030] Considering the overall structural dimensions and construction process of the instrument, this invention adopts an improved L-shaped Pitot tube structure, as shown in the figure below. When fluid flows through the Pitot tube, the central orifice of the nozzle receives both the static pressure and the maximum dynamic pressure of the airflow at that cross-section, while the small orifice on the outer tube wall only receives the static pressure. The differential pressure gauge measures the dynamic pressure, thereby achieving the purpose of Pitot tube velocity measurement.

[0031] (2) Measurement of dryness and flow rate in the wellbore ●The relationship between the steam density at the measuring point and the average velocity is obtained from the dynamic pressure measured by the Pitot tube.

[0032] The formula for measuring speed with a pitot tube is as follows: V1=((2*Δp) / ρ)^0.5 (1) V1—Steam point velocity, m / s; Δp — represents dynamic pressure difference, Pa; ρ—represents the density of the fluid, kg / m³ 3 .

[0033] The average velocity of steam in the wellbore is calculated based on the relationship between the flow point velocity and the average velocity. The Reynolds number for steam flowing in the pipe should generally be greater than 2300. Considering turbulent flow, the formula for calculating the average velocity is as follows: V=0.8V1 (2) V—Average velocity of steam across the cross section, m / s From (1) and (2), we get: V=((1.28*Δp) / ρ)^0.5 (3) This formula is applicable to a wide range of flow velocities. For gas flow measurement, the measurement range is from 1 m / s to 100 m / s, and for liquid flow measurement, it covers flow velocities from as low as 0.1 m / s to over 40 m / s. It covers all oil well steam injection testing ranges.

[0034] ●Given the injection rate and pipe diameter of the steam injection well, establish the relationship between the steam density in the wellbore and the average velocity based on the mass-energy equivalence of steam. Given the equivalent amount of water injected into the steam injection well, establish the relationship between steam velocity and density, and obtain the steam velocity value at the test point along the wellbore.

[0035] V=q / ρ·S (4) In the formula: —Steam mass flow rate, kg / s; ρ—Fluid density (steam, water), kg / m³ 3 ; S—Cross-sectional area of ​​the wellbore, in meters 2 .

[0036] ● By solving the two equations above simultaneously, the flow velocity and density of steam at the measuring point can be obtained; further calculation of the flow velocity yields the flow rate (volume, mass, and heat) of steam in the wellbore.

[0037] ●The steam dryness is obtained by combining the average steam density value with the relationship between steam density and dryness at that temperature.

[0038] Using the temperature and static pressure data of steam changes with depth in the steam injection wellbore obtained from the test, the density values ​​of saturated steam (dry steam) and saturated water (steam condensate) at the test point were calculated according to the density calculation formula of saturated steam (dry steam) and saturated water (steam condensate). (2) (3) In the formula: —Density of saturated water (condensate), kg / m³ 3 ; —Saturated steam (dry steam) density, kg / m³ 3 ; — represents the steam temperature, K (273+℃).

[0039] The relationship between steam dryness and density is as follows. Therefore, the steam dryness value at the test point can be calculated based on the steam density value calculated above. Multiple test points can be used to obtain a dryness profile.

[0040] (4) In the formula: —Steam density, kg / m³ 3 ; —Steam dryness, decimal.

[0041] (3) Measurement of dryness and flow rate within the oil reservoir The number of measuring points is determined based on the number of sub-layers in the oil reservoir. The temperature, pressure, dryness fraction, and flow rate parameters of each sub-layer are obtained according to the following process. That is, the dryness profile and steam absorption profile (volume, mass, and heat) of the oil reservoir.

[0042] The solution process is illustrated using three sub-layers as an example; the same method is used to solve for more sub-layers: ●One measuring point at the top boundary of the oil layer The following equations must be satisfied: V1=((1.28Δp) / ρ1)^0.5 (5) V1=q1 / ρ1S (6) We can obtain V1 and ρ1, and also obtain the temperature, pressure, dryness fraction, and flow rate (volume, mass, heat) at that point. ● Three small layers of interlayer with two measuring points The following equations must be satisfied: V2=((1.28Δp) / ρ2)^0.5 (7) V2=q2 / ρ2S (8) V3=((1.28Δp)2ρ3)^0.5 (9) V3=q3 / ρ3S (10) The density parameter at the top boundary measuring point has been determined; the density value of the oil layer section is calculated by combining the pressure gradient value at the measuring point. Therefore, the unknown parameters (mass flow rate and velocity) are solved by solving the corresponding linear equations in two variables.

Claims

1. A high-temperature four-parameter steam absorption profile tester based on an improved Pitot tube, characterized in that, include: The improved Pitot tube features both a full pressure port and a static pressure port; Temperature and pressure sensors; The data acquisition and storage module is used to record measured temperature, pressure, and differential pressure data; The collected data is used for subsequent calculations of steam flow rate and dryness.

2. The testing instrument according to claim 1, characterized in that: The diameter of the Pitot tube is designed to be 6mm, the diameter of the full pressure hole is designed to be (0.3-0.8D), taking 1.8mm, and the diameter of the static pressure hole is designed to be 1mm; the distance between the full pressure hole and the static pressure hole is (3-8D), taking 30-40mm, and the distance between the static pressure hole and the cut-off surface of the thermos bottle is 70-80mm.

3. The testing instrument according to claim 1, characterized in that: It also includes thermos bottles, which feature a vacuum-insulated design.

4. The testing instrument according to claim 1, characterized in that: The collected data is used to calculate steam parameters using the following formula: The flow velocity calculation module uses the formula: V=((1.28*Δp) / ρ)^0.5; The dryness calculation module uses the following formula: ; ； 。 5. A measurement method using the testing instrument described in claims 1-4, characterized in that... include: Go downhole to measure and store steam temperature, pressure, and differential pressure data; Export the collected data to a computing device; Calculate the steam flow rate and dryness based on the data; Obtain the vapor absorption profile of the oil reservoir.

6. The method according to claim 5, characterized in that: The calculation steps include: Calculate the flow velocity at each measuring point based on the differential pressure data; Calculate steam dryness by combining temperature and pressure data; Analyze the steam absorption situation in each oil layer section.

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